On Tue, Jun 17, 2008 at 4:58 PM, Gary <sql(at)4myad(dot)tv> wrote:
> Sorry to be such a pest. If I could understand these documents I probably
> wouldn't have to read them. I've been zipping around the net reading docs
> but nowhere do they start at the beginning.
Okay. Well, I'll try to give a little background information.
PostgreSQL is a Relational Database Management System (RDBMS).
Basically it purposed is to 1) implements and maintains physical
data-patterns that were defined to by a users conceptual database
design, 2) to safely accept and store data into the physical pattern,
3) return sets of data from the data pattern upon client request, 4)
change the data (and sometimes the data-pattern ) that it stores.
Note: A database data-pattern is usually referred to as a schema.
The schema is an implementation of how a particular database works
together as a whole.
PostgreSQL is installed with several shell/MS-DOS based client
programs that interact with PostgreSQL for the purposes of doing step
1 thru 4. The one that is most useful is psql (or psql.exe for a
windows installation). However, psql purpose is mostly to achieve
Now there is an important distinction that needs to be made between
PostgreSQL and a Database. PostgreSQL is a RDBMS. While a database
contains the physical implementation of a particular schema.
Basically Postgresql gives the breath of life to a database.
Another point to make about a database, is that a database is only as
good as the Conceptual Design that it implements. A good analogy
might be: PostgreSQL is to Microsoft Word, in the same way as a
database is to a Word document, and continuing the illustration, the
text of in a Word document is to a database Conceptual design/schema.
The purpose of the conceptual design is to adequately model the
reality of whose data one would want to store. This is necessary
since the designer wants to capture not only the important aspects of
the reality, but also how these aspects interrelate with one another.
So to make a valid point. A person who has no sense of spelling or
grammar should never expect to use MS-Word to create the worlds best
novel or poetry. Also a person who has no sense of conceptual
database design/ data modelling could ever expect to make a workable
database. Not to say that this can't be done. But in either case the
person must first learn the applicable skill for the task.
Up to this point we've said nothing about how to access this database.
And we've not mentioned how to do analysis on the data based upon the
relationships the exists between the data in a particular database.
This is where the Language of SQL comes into play.
Lastly as Client front-end programs also want to access that database
of the database. For the purpose of recording the important data of a
particular reality( usually a business process ). The Client
application needs to know information about the PostgreSQL Server
(server ip, Postgresql ip port, Postgresql database of interest, the
user and password that will be used to connect), the database ( the
database schema(data model), all of the tables, constraints, views,
indexes), and the SQL queries that it will use to efficiently interact
with that database.
> I've rediscovered how to start the interactive terminal and even listed the
> commands. Might as well be in Chinese.
I understand. If you read Chapters one and two it should answer
mosted of the basic questions:
> Seems like step 1 might be to determine the names of the data fields in the
> database. (tables & ?). How do I do that?
psql -U <yourdbusername> -d <databasename>
# \dt --list all the table in the public schema
# \d <a particular table name> -- see the columns of the table
#\? -- where to look for other useful commands
> Is there a newsgroup with "training wheels"?
This is the correct mailing list. However, instead of asking broad
vague questions. It is much better to ask many small specific
questions to specific mailing lists.
good questions example:
-- I cant' connect using psql. It throwing this error. What do I do?
-- I cant connect using ODBC. This is the error message when I try.
bad question example:
-- I don't get it. What do I do?
Richard Broersma Jr.
Visit the Los Angles PostgreSQL Users Group (LAPUG)
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